ccna chapter 1 pdf

ccna chapter 1 pdf.When a VLAN crosses different switches, how do computers on the same VLAN connected to different switch ports communicate? It is possible to add connections between switches for each VLAN. However, this will take up too many ports on the switch when there are multiple VLANs, and the scalability is very poor. The dominant solution is to use Trunking technology to communicate with hosts within VLANs across the switch. Trunk technology allows information from multiple VLANs to be transmitted on a single physical line. The switch receives data from a port belonging to a -* VLAN, and before it is transmitted on the Trunk link, it adds a tag that identifies.104.Cisco Networking Lab CCNA Lab Guide (Release 2) The VLAN to which the data belongs. the data arrives at the other switch. the switch removes the tag and sends it only to hosts that belong to the corresponding VLAN port. There are two common trunk frame tagging technologies: ISL (Inter-SwitchLink) and IEEE 802.lqo ISL technology is private to Cisco and re-encapsulates the original frame by adding a 26-byte frame header and a 4-byte frame check sequence (FCS), i.e., the ISL encapsulation is increased by 30 bytes. Because of the private nature of ISL, it is rarely used in practice and is not supported by Cisco's low-end switches such as the 2960. IEEE802.lq technology is the international standard and is supported by all manufacturers. This technology inserts a 4-byte tag (a 4-byte tag) after the source MAC address field of the original Ethernet frame.The IEEE 802.lq frame format is shown in Figure 8-1, and the meaning of each field with the 4-byte tag inserted is described below.Tag Protocol Identifier (TPID): 16 bits, this field is a fixed value of 0x8100.Priority (PRI): 3 bits, IEEE 802.Canonical Format Indicator (CFI): 1 bit, for Ethernet, this bit is 0.DATVLAN ID (VID): 12 bits, identifies the VLAN ID of the frame to which the frame belongsoDATAEEthernet II,Src:cc:00:14:54:00:00 (cc:00:14:54:00:00),Dst:cc:01:14:54:00:00 (cc:01:14:54:00:00) SIDestination: cc:01:14 :54:00:00 (cc:01 :14 :54 :00:00) @Source:cc:00:14:54:00:00 (cc:00:14:54:00:00)